Add LayerTreeHostClient::{will,did}UpdateLayer, report layer updates to DevTools

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index 57799f2e067b2037973547f8c85d896826031342..217c57311c92d34564709c4c0733395d9c2d8fcc 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -939,8 +939,10 @@ void RenderViewImpl::Initialize(RenderViewImplParams* params) {
   // The next group of objects all implement RenderViewObserver, so are deleted
   // along with the RenderView automatically.
   devtools_agent_ = new DevToolsAgent(this);
+  if (RenderWidgetCompositor* rwc = compositor()) {
+    webview()->devToolsAgent()->setLayerTreeId(rwc->GetLayerTreeId());
+  }
   mouse_lock_dispatcher_ = new RenderViewMouseLockDispatcher(this);
-
   new ImageLoadingHelper(this);
 
   // Create renderer_accessibility_ if needed.
@@ -2815,6 +2817,14 @@ void RenderViewImpl::didHandleGestureEvent(
                     DidHandleGestureEvent(event));
 }
 
+void RenderViewImpl::initializeLayerTreeView() {
+  RenderWidget::initializeLayerTreeView();
+  RenderWidgetCompositor* rwc = compositor();
+  if (!rwc || !webview() || !webview()->devToolsAgent())
+    return;
+  webview()->devToolsAgent()->setLayerTreeId(rwc->GetLayerTreeId());
+}
+
 // WebKit::WebFrameClient -----------------------------------------------------
 
 WebKit::WebPlugin* RenderViewImpl::createPlugin(WebFrame* frame,